Heat dissipating device for an electronic component

ABSTRACT

A heat dissipating device includes a lower heat sink unit and an upper heat sink unit stacked above the lower heat sink unit. The lower heat sink unit includes a base and a plurality of parallel fins extending from the base. Each of the fins has a top end distal from the base. The fins include a set of first fins and a set of second fins. Each of the first fins has a horizontal cross-section greater than that of each of the second fins. Each two adjacent ones of the first fins confine a horizontal spacing greater than that of each two adjacent ones of the second fins.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority of Taiwanese Application No. 091200918, filed on Jan. 29, 2002.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to a heat dissipating device, more particularly to a heat dissipating device for cooling an electronic component, such as a central processing unit.

[0004] 2. Description of the Related Art

[0005]FIG. 1 illustrates a conventional heat dissipating device 91 for cooling an electronic component (not shown), such as a central processing unit. The heat dissipating device 91 includes a heat sink base 92 and a plurality of plate-like fins 94, each of which has a root 93 fixed to the heat sink base 92. Each two adjacent fins 94 confine a spacing 95 therebetween for passage of air flow generated by a cooling fan (not shown).

[0006] The conventional heat dissipating device 91 is disadvantageous in that since the horizontal cross-section of the root 93 of each of the fins 94 is relatively small, heat conduction rate of heat flow from the root 93 of each fin 94 toward the remaining portion of the fin 94 is considerably restricted, thereby significantly reducing the overall heat dissipating efficiency of the heat dissipating device

[0007] As such, there is a need for a more effective heat dissipating device that can provide an increased cooling surface as compared to the aforesaid conventional device 91.

SUMMARY OF THE INVENTION

[0008] Therefore, the object of the present invention is to provide a heat dissipating device that is capable of overcoming the aforementioned drawback of the prior art.

[0009] According to the present invention, there is provided a heat dissipating device that comprises: a lower heat sink unit including a horizontally extending lower base and a plurality of spaced apart lower fins fixed to and extending upwardly from the lower base, each of the lower fins having a top end distal from the lower base; and an upper heat sink unit stacked above the lower heat sink unit and including a horizontally extending upper base that is fixed to the top ends of at least some of the lower fins, and a plurality of spaced apart upper fins fixed to and extending uprightly from the upper base. The lower fins include a set of parallel first lower fins and a set of second lower fins that are parallel to the first lower fins. Each of the first lower fins has a horizontal cross-section greater than that of each of the second lower fins. Each two adjacent ones of the first lower fins confine a horizontal spacing greater than that of each two adjacent ones of the second lower fins.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In drawings which illustrate embodiments of the invention,

[0011]FIG. 1 is a perspective view of a conventional heat dissipating device;

[0012]FIG. 2 is an exploded perspective view of a first preferred embodiment of a heat dissipating device according to this invention;

[0013]FIG. 3 is an assembled perspective view of the heat dissipating device of FIG. 2, which is cooled by a cooling fan;

[0014]FIG. 4 is an exploded perspective view of a second preferred embodiment of the heat dissipating device according to this invention;

[0015]FIG. 5 is a side view of the second preferred embodiment of this invention;

[0016]FIG. 6 is an exploded perspective view of a third preferred embodiment of the heat dissipating device according to this invention;

[0017]FIG. 7 is an exploded perspective view of a fourth preferred embodiment of the heat dissipating device according to this invention;

[0018]FIG. 8 is an exploded perspective view of a fifth preferred embodiment of the heat dissipating device according to this invention; and

[0019]FIG. 9 is a schematic view to illustrate how the heat dissipating device of this invention is cooled by an axial cooling fan and a centrifugal cooling fan.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] For the sake of brevity, like elements are denoted by the same reference numerals throughout the disclosure.

[0021]FIGS. 2 and 3 illustrate a first preferred embodiment of a heat dissipating device according to this invention for an electronic component 41, such as a central processing unit. The heat dissipating device includes: a lower heat sink unit 2 including a horizontally extending lower base 21 that is attached to the electronic component 41, and a plurality of spaced apart lower fins (22, 23) fixed to and extending upwardly from the lower base 21, each of the lower fins (22, 23) having a top end 20 distal from the lower base 21; and an upper heat sink unit 3 stacked above the lower heat sink unit 2 and including a horizontally extending upper base 31 that is fixed to the top ends 20 of at least some of the lower fins (22, 23) (in this preferred embodiment, the upper base 31 is fixed to the top ends 20 of all of the lower fins (22, 23)), and a plurality of spaced apart parallel upper fins 32 fixed to and extending uprightly from the upper base 31. The lower fins (22, 23) include a set of parallel first lower fins 22 and a set of second lower fins 23 that are parallel to the first lower fins 22. Each of the first lower fins 22 has a horizontal cross-section greater than that of each of the second lower fins 23. Each two adjacent ones of the first lower fins 22 confine a horizontal spacing 220 greater than the horizontal spacing 230 confined between each two adjacent ones of the second lower fins 23.

[0022] In this embodiment, each of the second lower fins 23 and each of the upper fins 32 is an elongated thin plate. The horizontal cross-section of each of the first lower fins 22 is substantially elliptical in shape, and has two opposite ends, each of which converges into a tip.

[0023] The second lower fins 23 include left and right sets of the second lower fins 23. The first lower fins 22 are disposed between the left and right sets of the second lower fins 23.

[0024] The upper base 31 has opposite top and bottom ends 313, 315 and opposite first and second sides 311, 314. Each of the first, and second sides 311, 314 is formed with an inclined side face 312 extending inclinedly and inwardly from the bottom end 315 to the top end 313 of the upper base 31. The upper fins 32, which are parallel to each other, define a plurality of air passages 320, each of which extends from the first side 311 to the second side 314. The inclined side face 312 at the first side 311 of the upper base 31 serves a guide for guiding air flow from an axial cooling fan 5 into the air passages 320.

[0025]FIGS. 4 and 5 illustrate a second preferred embodiment of the heat dissipating device according to this invention, which has a structure that is similar to that of the first embodiment shown in FIG. 2, except that each of the first lower fins 22 has a height greater than that of each of the second lower fins 23 such that the upper base 31 is fixed only to the top ends 20 of the first lower fins 22.

[0026]FIG. 6 illustrates a third preferred embodiment of the heat dissipating device according to this invention, which has a structure that is similar to that of the second embodiment shown in FIG. 4, except that the cross-section of each of the first lower fins 22 is rectangular in shape, and that the upper fins 32 are arranged in an array of parallel rows. The upper fins 32 in adjacent ones of the rows are staggered relative to each other.

[0027]FIG. 7 illustrates a fourth preferred embodiment of the heat dissipating device according to this invention, which has a structure that is similar to that of the second embodiment shown in FIG. 4, except that each of the upper fins 32 is in the form of a pin.

[0028]FIG. 8 illustrates a fifth preferred embodiment of the heat dissipating device according to this invention, which has a structure that is similar to that of the second embodiment shown in FIG. 4, except that each of the upper fins 32 has a horizontal cross-section that is substantially elliptical in shape and that has two opposite ends, each of which converges into a tip.

[0029]FIG. 9 illustrates how the heat dissipating device of this invention can be cooled by the axial cooling fan 5 and an centrifugal cooling fan 6 so as to increase the heat dissipating efficiency of the heat dissipating device of this invention.

[0030] Since each of the first lower fins 22 has a larger horizontal cross-section, the heat conduction rate of heat flow from the lower base 21 to the top ends 20 of the first lower fins 22 is higher as compared to that of the prior arts thereby eliminating the aforesaid drawback encountered in the prior art. Moreover, with the inclusion of the upper heat sink unit 3, the cooling surface of the heat dissipating device of this invention is significantly increased.

[0031] With the invention thus explained, it is apparent that various modifications and variations can be made without departing from the spirit of the present invention. It is therefore intended that the invention be limited only as recited in the appended claims. 

We claim:
 1. A heat dissipating device comprising: a lower heat sink unit including a horizontally extending lower base and a plurality of spaced apart lower fins fixed to and extending upwardly from said lower base, each of said lower fins having a top end distal from said lower base; and an upper heat sink unit stacked above said lower heat sink unit and including a horizontally extending upper base that is fixed to said top ends of at least some of said lower fins, and a plurality of spaced apart upper fins fixed to and extending uprightly from said upper base; wherein said lower fins include a set of parallel first lower fins and a set of second lower fins that are parallel to said first lower fins, each of said first lower fins having a horizontal cross-section greater than that of each of said second lower fins, each two adjacent ones of said first lower fins confining a horizontal spacing greater than that of each two adjacent ones of said second lower fins.
 2. The heat dissipating device of claim 1, wherein each of said first lower fins has a height greater than that of each of said second lower fins, said upper base being fixed to said top ends of said first lower fins.
 3. The heat dissipating device of claim 1, wherein each of said second lower fins is an elongated thin plate, said horizontal cross-section of each of said first lower fins being substantially elliptical in shape.
 4. The heat dissipating device of claim 1, wherein each of said second lower fins is an elongated thin plate, said horizontal cross-section of each of said first lower fins being rectangular in shape.
 5. The heat dissipating device of claim 2, wherein said second lower fins include left and right sets of said second lower fins, said first lower fins being disposed between said left and right sets of said second lower fins.
 6. The heat dissipating device of claim 1, wherein said upper fins are parallel to each other, each of said upper fins being an elongated thin plate.
 7. The heat dissipating device of claim 6, wherein each of said upper fins has a horizontal cross-section that is substantially elliptical in shape.
 8. The heat dissipating device of claim 6, wherein said upper fins are arranged in an array of parallel rows, said upper fins in adjacent ones of said rows being staggered relative to each other.
 9. The heat dissipating device of claim 6, wherein said upper base has opposite first and second sides and opposite top and bottom ends, each of said first and second sides being formed with an inclined side face extending inclinedly and inwardly from said bottom end to said top end of said upper base.
 10. The heat dissipating device of claim 1, wherein each of said upper fins is in the form of a pin. 